Open-Source Sleep Monitor and Modulator (OSSMM)

THIS REPOSITORY IS A WORK IN PROGRESS! PLEASE REFRAIN FROM USAGE UNTIL THIS TEXT IS REMOVED (Aprl 17th, 2025)

Introduction

Welcome! We present OSSMM, an Open-Source Sleep Monitor and Modulator platform. This is the world’s first open-source sleep monitoring and modulation platform

The goal of OSSMM is to provide researchers and sleep enthusiasts with an affordable hardware and software platform for conducting sleep research which can be built at the “home” lab. This cost-effective solution and local assembly encourages research across numerous participants within their natural home environment.

The target cost of OSSMM is below €40 (as of 12/2024) and we have achieved this! All components used are either commercially available at affordable prices, or 3D printed.

This system aims to assess sleep staging more accurately than many commercially available devices, like smartwatches and rings, at a fraction of the cost. Importantly, OSSMM is designed to permit researchers and enthusiasts to conduct experiments requiring sleep modulation, addressing a gap where no comparable system is currently available off-the-shelf.

OSSMM is currently under assessment for 4-stage sleep classification accuracy.

Key design considerations for OSSMM include:

  • Reusable silicone wet-dry electrodes. (no conductive gel needed)
  • Quick-change parts for easy repair and hygiene.
  • Battery powered with no exposed wiring (est. 15+ hour run-time)
  • Fully open-source hardware designs and software code.
    • Full access for user desired modification.
    • Full transparency of code and classification algorithms used for sleep staging.

System Overview (V1.0.2)

In short, OSSMM consists of a wearable headband that collects physiological data and transmits it wirelessly via Bluetooth Low Energy (BLE) to a dedicated smartphone application. Only Android is supported at this time.

Front view of OSSMM headband
Fig 1: Front of the OSSMM headband compared with a €1 coin.
Back view of OSSMM headband
Fig 2: Back of the OSSMM headband, with the silicone electrodes and PPG sensor visible.



The headband comprises:

  • 11 Components (Total part count excluding wires)
  • 3D printed housing
  • Four COTS boards
  • Rechargeable battery
  • Electrode head band (Elastic band with integrated silicone wet-dry electrodes, commercially available as a ‘heart rate monitor strap’)

Specifications:

  • Dimensions: 79.1 x 45.2 x 30 mm (3.114 x 1.780 x 1.181 in)
  • Weight: 76.5 grams ( or 2.7 ounces with a 150 mAh battery)
  • Sampling Frequency: up to 250Hz (produces 500MB for 8 hour recording)
  • Battery: 120-220 mAh (est. 15-27.5 hour run time of only sleep monitoring)

The device currently collects the following data:

  • Head movement: Via onboard Inertial Measurement Unit (IMU)
  • Eye movement: Electrooculography (EOG)
  • Brain signatures: Frontal Electroencephalography (EEG)
  • Heart rate: Photoplethysmography (PPG)

Additional Notes:

While the hardware supports sound data collection via a microphone, this feature is not activated in version 1.0.2.

Collected data is transmitted via BLE to a smartphone running the OSSMM app. The app stores the raw data locally. Future versions aim to analyze data in near-real-time (e.g. after 1-2 epochs, or 30-60seconds) to potentially trigger sleep modulation if desired within the experimental protocol.

OSSMM V1.0.2 uses a COTS vibration motor (similar to those in mobile phones) as a stimulus mechanism for sleep modification experiments. The vibration motor serves as an ideal example stimulus from an engineering perspective due to its heavy power demands.

In other words, since the system can successfully handle a vibration motor that consumes large amounts of current during operation (+60 mA), it can easily accommodate other stimulus methods: speaker, LEDs, tDCS, and tACS.

Documentation Guide

This documentation provides the necessary information to build, set up, and understand the OSSMM V1.0.2. Please follow the sections below in order:

  1. Prerequisites: Detailed introduction and required software, tools, components, and background skills.
  2. 3D Printables: Instructions for printing the device’s 3D printed casing.
  3. Electronics Assembly: Step-by-step guide for soldering and assembling the electronic hardware components.
  4. Software Setup: Instructions for uploading code onto the microcontroller (MCU) and setting up the smartphone application.
  5. Final Assembly & Completion: Integrating the electronics into the casing, attaching the headband, and final checks.

Safety Considerations

User safety was a fundamental priority throughout the development of OSSMM. The design incorporates several important safety features:

  • Low-voltage electronics: All electronic components are commercially available, hobbyist-grade parts commonly used in wearable maker projects. The system operates entirely on low voltage, minimizing electrical risks.

  • Limited battery capacity: The small-capacity battery (120-220 mAh) significantly reduces potential risks associated with battery malfunctions.

  • Non-invasive sensors: With the exception of the pulse sensor, all measurement systems are passive. The pulse sensor uses photoplethysmography (PPG) - the same light-based technology found in consumer smartwatches - which emits only low-intensity light to detect blood flow beneath the skin. At no point is current injected into the body

  • Biocompatible materials: We selected specific 3D printing filaments based on their published safety data to ensure skin contact compatibility. Safety data sheets for all components and filaments are included in this repository for your reference.

While we’ve made every effort to design a safe system, users assume responsibility for their implementation. We cannot be held liable for any use, misuse, or adverse events resulting from the construction or operation of an OSSMM device. It remains the user’s responsibility to properly assemble their device using appropriate components from reputable sources and to ensure proper operation. This is not a medical device.

Data Privacy and Security

OSSMM was designed with data protection as a concern:

  • Secure BLE connection: The smartphone-to-device BLE connection requires verification of 3 unique UUIDs before data transmission occurs.

  • User-customizable security: Each user can modify these UUID values to create their own unique security profile.

  • Local data storage: All data collected by OSSMM is stored locally on your smartphone in a dedicated “/OSSMM” directory. No data is automatically transmitted to external servers or cloud services, unless you choose to do so.

  • Device security recommendations: Due to the sensitive nature of sleep and physiological data, we recommend that smartphones used with OSSMM be secured with PIN codes or other access controls.

Current Version: V1.0.2